1. Field of the Invention
Embodiments of the present invention generally relate to method and apparatus for processing a semiconductor substrate. More particularly, embodiments of the present invention relate to method and apparatus for cleaning a surface of a silicon substrate.
2. Description of the Related Art
Integrated circuits are formed in and on silicon and other semiconductor substrates. In the case of single crystal silicon, substrates are made by growing an ingot from a bath of molten silicon, and then sawing the solidified ingot into multiple wafers. An epitaxial silicon layer may then be formed on the monocrystalline silicon wafer to form a defect free silicon layer that may be doped or undoped. Semiconductor devices, such as transistors, are manufactured from the epitaxial silicon layer. The electrical properties of the formed epitaxial silicon layer will generally be better than the properties of the monocrystalline silicon substrate.
Surfaces of the monocrystalline silicon and the epitaxial silicon layer are susceptible to contamination when exposed to typical ambient conditions. Therefore, a substrate needs to be cleaned to remove impurities and particles found on silicon wafer surface prior to performing various semiconductor processes, such as the formation of an epitaxial layer.
Conventionally, semiconductor substrates are cleaned using wet cleaning processes or conventional plasma cleaning process. However, wet cleaning processes have “queue time” issues, which can cause wafer to wafer variation in wafer lots due to varying idle times for different wafers in a lot. Conventional remote or in-situ plasma cleaning processes can be very challenging due to the contamination of the chamber and substrates processed in the chamber due to the creation of unwanted species that are formed in the gas phase or during the cleaning process. These unwanted species either limit the cleaning action of the desired species or introduce other complications to the cleaning process.
Therefore, there is a need for method and apparatus for cleaning a substrate surface, especially for cleaning a substrate surface prior to performing an epitaxial deposition process.